It is hard to believe after this destruction of West Ham that only a few weeks ago Sunderland were being tipped for relegation and David Vaughan was unwanted by Martin O'Neill.
Performances were bad enough to put O'Neill under pressure. Sunderland could not score unless Steven Fletcher did. They looked weak in defence, lightweight in midfield and lacked creative spark.
They rebuilt over Christmas, beating Manchester City on St Stephen's Day. The recovery was down to hard work and determination but, for the first time on Saturday, they played like a team that could be destined for better things.
From back to front, they were superb. Titus Bramble and John O'Shea were immense at the back, Adam Johnson looked like an England player again, Stephane Sessegnon looked ready to grace any stage and James McClean was a bustling bundle of energy on the wing.
None of them, though, could beat Vaughan to the Man of the Match award. The Wales international was the busy midfield metronome that made Sunderland tick.
Punished for an awful performance against Middlesbrough in October, Vaughan looked unlikely to get another look-in until injuries mounted. "He started against Bolton (in the FA Cup) and he was our best player," said O'Neill, who retained Vaughan ahead of new signing Alfred N'Diaye. "He was trying to get it down and manoeuvre it. He was excellent."
West Ham fell behind to an excellent strike from Sebastian Larsson, but Sam Allardyce described their defending for the other two goals, from Johnson and McClean, as "pathetic". The manager said his side looked "woefully short" of what they need to avoid relegation and his misery was compounded by James Collins tearing a hamstring.
Meanwhile, Joey O'Brien has committed his future to West Ham until 2016 by agreeing a new deal. The 26-year-old Ireland defender joined the Hammers on a free transfer in 2011 after he was released by Bolton Wanderers.